Monitoring device, motor driving apparatus, and monitoring method

Abstract

A monitoring device includes: an acquisition unit for acquiring a clock signal output from a communication circuit that outputs the clock signal; and a monitoring unit for analyzing the waveform of the clock signal acquired by the acquisition unit, based on a predetermined reference clock signal having a period equal to or shorter than a period of the clock signal to thereby determine whether or not there is a sign of malfunction in the communication circuit.

What is claimed is: 
     
       1. A monitoring device, comprising:
 an acquisition unit configured to acquire a clock signal output from a communication circuit that outputs the clock signal; and 
 a monitoring unit configured to analyze a waveform of the clock signal acquired by the acquisition unit, based on a predetermined reference clock signal having a period equal to or shorter than a period of the clock signal, and thereby determine whether or not there is a sign of malfunction in the communication circuit. 
 
     
     
       2. The monitoring device according to  claim 1 , wherein the monitoring unit is configured to determine that there is a sign of malfunction in the communication circuit when the analyzed waveform of the clock signal is different from a predetermined basic waveform. 
     
     
       3. The monitoring device according to  claim 2 , wherein the monitoring unit is configured to analyze the waveform of the clock signal by observing voltage level of the clock signal at rising or falling timings of the reference clock signal. 
     
     
       4. The monitoring device according to  claim 3 , wherein the monitoring unit is configured to determine that there is a sign of malfunction in the communication circuit when a time period during which the voltage level of the clock signal is kept at a high level or a low level is equal to or longer than a time threshold. 
     
     
       5. A motor driving apparatus comprising the monitoring device according to  claim 1 , further comprising:
 an inverter configured to supply an electric current to a motor; 
 a current detector configured to detect the electric current supplied to the motor; and 
 a control unit configured to control the inverter, wherein: 
 the communication circuit is configured to output the clock signal and data corresponding to a detection signal detected by the current detector, to the control unit; and 
 the control unit is configured to output the reference clock signal to the monitoring unit. 
 
     
     
       6. A monitoring method, comprising:
 an acquisition step of, with an acquisition unit, acquiring a clock signal output from a communication circuit that outputs the clock signal; and 
 a monitoring step of, with a monitoring unit, determining whether or not there is a sign of malfunction in the communication circuit, by analyzing a waveform of the clock signal, based on a predetermined reference clock signal having a period that is equal to or shorter than a period of the clock signal. 
 
     
     
       7. The monitoring method according to  claim 6 , wherein the monitoring step determines that there is a sign of malfunction in the communication circuit when the analyzed waveform of the clock signal is different from a predetermined basic waveform. 
     
     
       8. The monitoring method according to  claim 7 , wherein the monitoring step analyzes the waveform of the clock signal by observing voltage level of the clock signal at rising or falling timings of the reference clock signal. 
     
     
       9. The monitoring method according to  claim 8 , wherein the monitoring step determines that there is a sign of malfunction in the communication circuit when a time period during which the voltage level of the clock signal is kept at a high level or a low level is equal to or longer than a time threshold. 
     
     
       10. The monitoring method according to  claim 6 , wherein the reference clock signal is supplied from a control unit configured to control an inverter that supplies an electric current to a motor, to the monitoring unit.